Norbornene, which is a bridged six-membered carbon ring with a double bond at one side thereof, exhibits high reactivity because of the double bond and may thus be applied not only to optical materials, such as optical fibers, CD-ROMs and optical lenses but also to modified polymer materials, etc., and is thereby regarded as highly useful. In particular, polynorbornene known as a shape memory polymer resulting from polymerizing norbornene is efficiently utilized in medical machines, vehicle parts and living goods.
Meanwhile, a plasticizer added to products is a liquid or solid material which decreases the melting temperature and melting viscosity of rubber and plastics to increase processability and flexibility. A good plasticizer has low volatility, stability in heat and cold, flexibility at low temperature, high miscibility with rubber and plastics, and low efflux. In addition, a plasticizer is used to improve functions including electrical insulation properties, adhesion, cold resistance, etc. Currently, a plasticizer is mainly added to synthetic resin.
A phthalate-based plasticizer, including dioctyl phthalate (DOP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), diisononyl phthalate (DINP), polyethyleneterephthalate (PET), etc., an adipate-based plasticizer, including dioctyl adipate (DOA), diisononyl adipate (DINA), etc., a fatty acid-based plasticizer, a phosphoric acid-based plasticizer, and a polyester-based plasticizer have been used. Particularly useful as the plasticizer is DOP which constitutes 72% of domestic plasticizer production.
DOP which started to be used in the 1930s is synthesized from phthalic acid and 2-ethylhexyl alcohol, and is very effective at increasing the processability of polyvinyl chloride resin. However, three kinds of phthalate-based plasticizers, including DOP, DBP and BBP, are indicated as suspected endocrine disrupters. The phthalate-based plasticizer was proven to have carcinogenicity, mutation-causing toxicity, and reproduction toxicity by the Scientific Committee on Toxicity, Ecotoxicity and the Environment of the EU, 2005, and thus the use thereof was banned.
In Korea, the phthalate-based plasticizer is classified as an environmental hormone material and thus the application thereof to all plastic toys and children's products has been banned from 2006. Because of the harmfulness of the phthalate-based plasticizer, the development of an eco-friendly plasticizer which can replace such a phthalate-based plasticizer is required.